Method and device for controlling a vehicle braking system in open loop

Abstract

A method and a device for controlling a vehicle braking system in open loop, having electrically operable control devices at the wheel brakes. The control device is controlled according to a driver's braking input, in at least one operating state, on the basis of the correlation, adjusted by an estimate method, between a variable representing the path of the brake pad, and the braking torque or the braking force at the wheel, and/or on the basis of the zero value of this variable, ascertained by an estimate method, when the brake pads lift off from the disc or drum.

What is claimed is:  
     
       1. A method for controlling according to a control arrangement a vehicle braking system including a plurality of electrically operable control devices provided at wheel brakes of a vehicle including the vehicle braking system, comprising the steps of: 
       determining a variable representing a path of a brake pad of the vehicle braking system;  
       measuring one of a braking torque and a braking force at at least one wheel associated with the wheel brakes;  
       determining a correlation between the variable representing the path of the brake pad and one of the braking torque and the braking force;  
       adjusting the correlation by performing a first estimate method;  
       when the brake pad lifts off from one of an associated brake disc and a brake drum of the vehicle braking system, ascertaining a zero value of the variable representing the path of the brake pad by performing a second estimate method; and  
       controlling at least one of the plurality of electrically operable control devices according to a braking input provided by a driver of the vehicle, wherein the at least one of the plurality of electrically operable control devices is controlled on the basis of at least one of the correlation and the zero value.  
     
     
       2. The method according to claim  1 , wherein each one of the first estimate method and the second estimate method is performed according to one of an online arrangement and an offline arrangement. 
     
     
       3. The method according to claim  1 , wherein the step of determining the correlation includes the step of preselecting the correlation as a quadratic equation having parameters determined by a third estimate method. 
     
     
       4. The method according to claim  1 , wherein at least one of the correlation and the zero value is adapted by a corresponding one of the first estimate method and the second estimate method to a wear and tear value, a temperature value, and a sensor offset value. 
     
     
       5. The method according to claim  1 , wherein the control arrangement is carried out on the basis of one of the braking torque and the braking force, without a sudden change resulting during a switchover operation. 
     
     
       6. The method according to claim  1 , wherein at least one of the correlation and the zero value are constantly adapted as a result of a corresponding one of the first estimate method and the second estimate method being performed according to an online arrangement. 
     
     
       7. The method according to claim  1 , wherein at least one of the first estimate method and the second estimate method corresponds to a least error squares method. 
     
     
       8. The method according to claim  1 , wherein the variable representing the path of the brake pad corresponds to a rotational angle of an electric motor associated with the one of the plurality of electrically operable control devices. 
     
     
       9. The method according to claim  1 , further comprising the step of: 
       calculating one of the braking torque and the braking force as a function of the variable representing the path of the brake pad, the zero value, and estimated parameters of the correlation.  
     
     
       10. A device for controlling a vehicle braking system of a vehicle according to a control arrangement, comprising: 
       a plurality of electrically operable control devices provided at wheel brakes of the vehicle braking system;  
       an arrangement for determining a variable representing a path of a brake pad of the vehicle braking system;  
       an arrangement for measuring one of a braking torque and a braking force at a wheel associated with one of the wheel brakes;  
       an arrangement for determining a correlation between the variable representing the path of the brake pad and the one of the braking torque and the braking force;  
       an arrangement for adjusting the correlation according to a first estimate method;  
       ascertaining a zero value of the variable representing the path of the brake pad according to a second estimate method, when the brake pad lifts off from one of an associated brake disc and a brake drum of the vehicle braking system; and  
       an arrangement for controlling at least one of the plurality of electrically operable control devices according to a braking input provided by a driver of the vehicle, wherein, in at least one operating state, the at least one of the plurality of electrically operable control devices is controlled on the basis of at least one of the correlation and the zero value.